it.unimi.dsi.util

Class SplitMix64Random

java.lang.Object

java.util.Random

it.unimi.dsi.util.SplitMix64Random

All Implemented Interfaces:

Serializable

public class SplitMix64Random
extends Random

A fast, top-quality, non-splittable version of the SplitMix pseudorandom number generator used by Java 8's SplittableRandom. Due to the fixed increment constant and to different strategies in generating finite ranges, the methods of this generator are usually faster than those of SplittableRandom.

Note that this generator has a relatively short period (2⁶⁴) so it should not be used to generate very long sequences (the rule of thumb to have a period greater than the square of the length of the sequence you want to generate).

See Also:

it.unimi.dsi.util, Random, SplitMix64RandomGenerator, Serialized Form

Constructor Summary

Constructors

Constructor and Description
SplitMix64Random() Creates a new generator seeded using Util.randomSeed().
SplitMix64Random(long seed) Creates a new generator using a given seed.

Method Summary

Modifier and Type	Method and Description
boolean	nextBoolean()
void	nextBytes(byte[] bytes)
double	nextDouble()
float	nextFloat()
int	nextInt()
int	nextInt(int n)
long	nextLong()
long	nextLong(long n) Returns a pseudorandom uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.
void	setSeed(long seed) Sets the seed of this generator.
void	setState(long state) Sets the state of this generator.

Methods inherited from class java.util.Random

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, next, nextGaussian

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SplitMix64Random

public SplitMix64Random()

Creates a new generator seeded using Util.randomSeed().

SplitMix64Random

public SplitMix64Random(long seed)

Creates a new generator using a given seed.

Parameters:

seed - a nonzero seed for the generator (if zero, the generator will be seeded with -1).

Method Detail

nextLong

public long nextLong()

Overrides:

nextLong in class Random

nextInt

public int nextInt()

Overrides:

nextInt in class Random

nextInt

public int nextInt(int n)

Overrides:

nextInt in class Random

nextLong

public long nextLong(long n)

Returns a pseudorandom uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The algorithm used to generate the value guarantees that the result is uniform, provided that the sequence of 64-bit values produced by this generator is.

Parameters:

n - the positive bound on the random number to be returned.

Returns:

the next pseudorandom long value between 0 (inclusive) and n (exclusive).

nextDouble

public double nextDouble()

Overrides:

nextDouble in class Random

nextFloat

public float nextFloat()

Overrides:

nextFloat in class Random

nextBoolean

public boolean nextBoolean()

Overrides:

nextBoolean in class Random

nextBytes

public void nextBytes(byte[] bytes)

Overrides:

nextBytes in class Random

setSeed

public void setSeed(long seed)

Sets the seed of this generator.

The seed will be passed through HashCommon.murmurHash3(long).

Overrides:

setSeed in class Random

Parameters:

seed - a seed for this generator.

setState

public void setState(long state)

Sets the state of this generator.

Parameters:

state - the new state for this generator (must be nonzero).